E07550: must return an Integer

What went wrong

A function or method is required to return Integer but returns a different type.

Worked examples

Compilable examples demonstrating this error and the correct fix:

• ek9 -q 779 (Why must certain operators return a value in EK9?)
• ek9 -q 239 (How do comparison and ordering operators work in EK9?)
• ek9 -q 238 (What operators does EK9 support and why is the set fixed?)
• ek9 -q 242 (How do conversion and introspection operators work in EK9?)
• ek9 -q 245 (How do I implement all the operators my custom type needs?)

How to fix it

1. Change return type to Integer

Common causes

• Comparison operator (<=>) returning wrong type
• Counter/index function type mismatch

See also

• E07550: Integer return required (this error)
• E07520: Boolean return required
• E07570: String return required

Examples

Every example is compiled by the EK9 compiler: the first fails exactly as captioned, the others fix it.

Fails with E07550: must return an Integer

#!ek9
defines module error.e07550.bad

  defines class

    Score
      points as Integer: 0

      //'<=>' answers less, equal or greater as an Integer
      operator <=> as pure
        -> other as Score
        <- rtn as Score: this

      default operator ?

      operator #? as pure
        <- rtn as Integer: #?points

Fixed: '<=>' returns an Integer: less, equal or greater

#!ek9
defines module error.e07550.good.fix

  defines class

    Score
      points as Integer: 0

      //'<=>' answers less, equal or greater as an Integer
      operator <=> as pure
        -> other as Score
        <- rtn as Integer: points <=> other.points

      default operator ?

      operator #? as pure
        <- rtn as Integer: #?points

Fixed: Return an Integer

#!ek9
defines module error.e07550.good

  defines class

    Score
      points as Integer?

      default private Score()

      Score()
        -> initial as Integer
        this.points: initial

      total() as pure
        <- rtn as Integer: points

      //Negative, zero or positive
      operator <=> as pure
        -> other as Score
        <- rtn as Integer: points <=> other.total()

      operator #? as pure
        <- rtn as Integer: #?points

      override operator ? as pure
        <- rtn as Boolean: points?

Questions and answers

These Q&A entries show E07550 and its fix:

• Q238: What operators does EK9 support and why is the set fixed?
• Q239: How do comparison and ordering operators work in EK9?
• Q242: How do conversion and introspection operators work in EK9?
• Q245: How do I implement all the operators my custom type needs?
• Q779: Why must certain operators return a value in EK9?
• Q911: What does the #? operator mean in EK9?
• Q1053: Implement #? manually on a class that combines multiple fields.
• Q1229: Select the higher-priority Task from two optional task records.